This was Andy's fifth grand slam final, and having sat through four already I had an idea of what it was going to feel like. But I was still very nervous – I was desperate for him to get over that final hurdle and achieve what has been his goal since he was a little boy. I think it's called the righting reflex – where you want to make everything right for your child, but you know there's absolutely nothing you can do about it.

In New York the crowd is particularly buoyant, so it was noisy and lively, and conditions were quite windy at the start, which made it tricky. But after two sets he was 2-0 up, and he's one of the fittest guys out there – it was a huge opportunity. I've been in tennis and in sport too long to know that it's not over until the last ball's hit. When it went to two sets all, I was mentally rehearsing, imagining: "What if this set doesn't go his way?" After he'd lost the Wimbledon final we tried to keep his spirits up, make sure he was doing lots of things he would enjoy, getting him out of the house. As a parent there's a huge job there, trying to help him to recover emotionally.

Andy took a bathroom break after the fourth set and when he came out he looked up, clenched his fist and stared for a bit; I could just see something in his face that was saying: "I'm not letting this go." And he played an unbelievable fifth set. That last shot that Novak Djokovic hit, at matchpoint? I wasn't sure that it was definitely out, and I thought: "There's no point in jumping up and getting too excited in case there's a replay and you look like an absolute idiot." So I just stood there staring at the screen until they said he had won. The emotion was incredible relief.

We booked a restaurant near Times Square that night – for his girlfriend, some friends from Dunblane, his team – but with all the media he had to do it was late by the time we got there and when we left it was 1.30am. The next morning he was up at 6am for his first TV commitment. He didn't get much sleep.